I have some dim memory of there being some ACPI reason why it had to be done that way.

In fact, this was done in commit e3c7db621bed4afb8e231cb005057f2feb5db557, long ago, by Rafael:

As indicated in a recent thread on Linux-PM, it's necessary to call pm_ops->finish() before devce_resume(), but enable_nonboot_cpus() has to be called before pm_ops->finish() (cf.http://lists.osdl.org/pipermail/linux-pm/2006-November/004164.html). For consistency, it seems reasonable to call disable_nonboot_cpus() after device_suspend().

This way the suspend code will remain symmetrical with respect to the resume code and it may allow us to speed up things in the future by suspending and resuming devices and/or saving the suspend image in many threads.

The following series of patches reorders the suspend and resume code so that nonboot CPUs are disabled after devices have been suspended and enabled before the devices are resumed. It also causes pm_ops->finish() to be called after enable_nonboot_cpus() wherever necessary.

Hmm?

It's entirely possible that that commit was simply just buggy, and we should indeed move the CPU down/up to be early/late - we've fixed other ordering issues since that commit went in. But this whole area is very murky.

(Btw, the above commit message points to just my response with a testing patch to the real email: the actual explanation of the INSANE ordering is from Len Brown in

I personally think that the whole ACPI ordering requirements are just insane, but the point of this email is to point these different requirements out, and hopefully we can get something that works for everybody.

Len added to Cc.

Len? Thomas wants to call 'disable_nonboot_cpus()' early, and 'enable_nonboot_cpus()' late. Can you explain why that is wrong?